Zoom lens and imaging apparatus

ABSTRACT

The zoom lens includes, in order from the object side: a first lens group G 1  that has a positive refractive power and remains stationary during zooming; a plurality of movable lens groups that move by changing distances between groups adjacent to each other in a direction of an optical axis during zooming; and a final lens group Ge that has a positive refractive power and remains stationary during zooming. At least one movable lens group has a negative refractive power. The first lens group G 1  has an image side positive lens, which is a positive lens disposed to be closest to the image side, and one or more positive lenses which are disposed to be closer to the object side than the image side positive lens. The zoom lens satisfies predetermined conditional expressions relating to the image side positive lens.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2016/081133 filed on Oct. 20, 2016, which claims priority under 35U.S.C § 119(a) to Japanese Patent Application No. 2016-013136 filed onJan. 27, 2016. Each of the above application(s) is hereby expresslyincorporated by reference, in its entirety, into the presentapplication.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a zoom lens suitable for movie imagingcameras, broadcast cameras, digital cameras, video cameras, andsurveillance cameras, and to an imaging apparatus comprising the zoomlens.

2. Description of the Related Art

In the related art, a zoom lens having a four-group configuration or afive-group configuration has been proposed as a lens system that can beused for cameras in the above-mentioned fields. For movie imagingcameras and broadcast cameras, the change in the total length of thelens system caused by zooming and the change in the angle of view causedby focusing are undesirable. Therefore, in most cases, the first lensgroup, which is a lens group closest to the object side in the zoomlens, is made to remain stationary during zooming, and focusing isperformed by using the lenses in the first lens group during focusing.For example, JP2015-94866A and JP5777225B each disclose lens systems aszoom lenses of a four-group configuration or a five-group configuration.In each lens system, the first lens group includes, in order from theobject side, a negative lens group that remains stationary duringfocusing, a positive lens group that moves during focusing, and apositive lens group that remains stationary during focusing.

SUMMARY OF THE INVENTION

In the past, in the lens system in which focusing is performed using thefirst lens group as described above, the first lens group tends tobecome large due to the focusing method. Meanwhile, in cameras in theabove-mentioned field, it is desired that a higher-resolution image canbe acquired with a higher zoom ratio. In order to obtain ahigh-resolution image, it is necessary to satisfactorily correctchromatic aberration of the lens system to be mounted. However, in acase where the configuration is intended to be applied, the number oflenses of the first lens group tends to be large, and this leads to anincrease in size of the first lens group. There is a demand for a lenssystem which can be configured to have a small size by minimizing thenumber of lenses of the first lens group and in which a high zoom ratioand high performance are achieved.

However, in the lens system described in JP2015-94866A, the number oflenses of the first lens group is large and reduction in size is notachieved, or the zoom ratio is insufficient. Further, in the lens systemdescribed in JP2015-94866A, longitudinal chromatic aberration at thetelephoto end is large in a case where the aperture diameter of theaperture stop is set to be constant over the entire zoom range.Therefore, in this lens system, there is a disadvantage that the axialmarginal ray should be shielded by using a member other than theaperture stop in a part of the zoom range so as not to cause largelongitudinal chromatic aberration. It is desired that the lens systemdescribed in JP5777225B has a higher zoom ratio in order to meet therecent demands.

The present invention has been made in consideration of theabove-mentioned situations, and its object is to provide a zoom lenswhich can be configured to have a small size while ensuring a high zoomratio and has high optical performance by satisfactorily correctingchromatic aberration, and an imaging apparatus comprising the zoom lens.

A zoom lens of the present invention comprises, in order from an objectside: a first lens group that has a positive refractive power andremains stationary with respect to an image plane during zooming; aplurality of movable lens groups that move by changing distances betweengroups adjacent to each other in a direction of an optical axis duringzooming; and a final lens group that has a positive refractive power andremains stationary with respect to the image plane during zooming. Inthe plurality of movable lens groups, at least one movable lens grouphas a negative refractive power. The first lens group has an image sidepositive lens, which is a positive lens disposed to be closest to theimage side, and one or more positive lenses which are disposed to becloser to the object side than the image side positive lens. Inaddition, all Conditional Expressions (1) to (5) are satisfied.

0.25<fl/fz<0.7  (1)

55<νz<68  (2)

15<νmx−νz<50  (3)

2.395<Nz+0.012×νz  (4)

0.634<θgFz+0.001625×νz<0.647  (5)

Here, fl is a focal length of the first lens group,

fz is a focal length of the image side positive lens,

νz is an Abbe number of the image side positive lens at the d line,

νmx is an Abbe number of a positive lens, of which the Abbe number atthe d line is at a maximum value, among positive lenses disposed to becloser to the object side than the image side positive lens,

Nz is a refractive index of the image side positive lens at the d line,and

θgFz is a partial dispersion ratio of the image side positive lensbetween the g line and the F line.

It is preferable that the zoom lens of the present invention satisfiesConditional Expression (6).

1.2<ft/fl<2.8  (6)

Here, ft is a focal length of the whole system at a telephoto end, and

fl is a focal length of the first lens group.

It is preferable that the zoom lens of the present invention satisfiesConditional Expression (7).

0.1<fw/fl<0.4  (7)

Here, fw is a focal length of the whole system at a wide-angle end, and

fl is a focal length of the first lens group.

In the zoom lens of the present invention, focusing may be performed bymoving one or more lenses in the first lens group in the direction ofthe optical axis.

In the zoom lens of the present invention, it is preferable that in theplurality of movable lens groups, a movable lens group closest to theimage side has a negative refractive power.

In the zoom lens of the present invention, the plurality of movable lensgroups may be configured to include a lens group having a negativerefractive power and a lens group having a negative refractive power.Alternatively, the plurality of movable lens groups may be configured toinclude, in order from the object side, a lens group having a positiverefractive power, a lens group having a negative refractive power, and alens group having a negative refractive power. Alternatively, theplurality of movable lens groups may be configured to include, in orderfrom the object side, a lens group having a negative refractive power, alens group having a positive refractive power, and a lens group having anegative refractive power.

The first lens group of the zoom lens of the present invention may beconfigured to include, in order from the object side, a first lens groupfront group that has a negative refractive power and remains stationarywith respect to the image plane during focusing, a first lens groupintermediate group that has a positive refractive power and moves in thedirection of the optical axis during focusing, and a first lens grouprear group that is set such that a distance in the direction of theoptical axis between the first lens group rear group and the first lensgroup intermediate group changes during focusing and has a positiverefractive power.

In a case where the first lens group includes the three lens groups, itis preferable that Conditional Expression (8) is satisfied.

0.5<flc/fz<0.7  (8)

Here, flc is a focal length of the first lens group rear group, and

fz is a focal length of the image side positive lens.

In a case where the first lens group includes the three lens groups, itis preferable that the first lens group front group has at least onenegative lens that satisfies Conditional Expressions (9) and (10).

55<νn  (9)

0.635<θgFn+0.001625×νn<0.675  (10)

Here, νn is an Abbe number of the negative lens of the first lens groupfront group at the d line, and

θgFn is a partial dispersion ratio of the negative lens of the firstlens group front group between the g line and the F line.

In a case where the first lens group includes the three lens groups, thefirst lens group rear group may be configured to have, successively inorder from the object side, a cemented lens which is formed by cementinga negative lens and a positive lens in order from the object side, and apositive lens.

In a case where the first lens group includes the three lens groups, thefirst lens group rear group may be configured to remain stationary withrespect to the image plane during focusing.

In the zoom lens of the present invention, instead of each ofConditional Expressions (1) to (3) and (6) to (8), it is more preferablethat each of Conditional Expressions (1-1) to (3-1) and (6-1) to (8-1)is satisfied.

0.35<fl/fz<0.65  (1-1)

56<νz<65  (2-1)

30<νmx−νz<45  (3-1)

1.5<ft/fl<2.5  (6-1)

0.11<fw/fl<0.35  (7-1)

0.55<flc/fz<0.68  (8-1)

An imaging apparatus of the present invention comprises the zoom lens ofthe present invention.

In the present specification, it should be noted that the term“substantially consisting of ˜” and “substantially consists of ˜” meansthat the imaging lens may include not only the above-mentioned elementsbut also lenses substantially having no powers, optical elements, whichare not lenses, such as a stop, and/or a cover glass, and mechanismparts such as a lens flange, a lens barrel, and/or a camera shakingcorrection mechanism.

It should be noted that the “lens group” is not necessarily composed ofa plurality of lenses, but may be composed of only one lens. The above“˜ lens group having a positive refractive power” and “˜ lens grouphaving a negative refractive power” each represent the sign of therefractive power of the corresponding lens group as a whole. Signs ofrefractive powers of the lens groups and signs of refractive powers ofthe lenses are assumed as those in paraxial regions in a case where somelenses have aspheric surfaces. All the conditional expressions areassumed to be in a state where the object at infinity is in focus. Inaddition, the conditional expressions are assumed to relate to the dline (a wavelength of 587.6 nm, nm: nanometers) unless otherwise noted.

It should be noted that the partial dispersion ratio θgF between the gline and the F line of a certain lens is defined by θgF=(Ng−NF)/(NF−NC),where Ng, NF, and NC are the refractive indices of the lens at the gline, the F line, and the C line.

According to the present invention, the zoom lens consists of, in orderfrom the object side, the first lens group that has a positiverefractive power and remains stationary during zooming, the plurality ofmovable lens groups that move during zooming, and the final lens groupthat has a positive refractive power and remains stationary duringzooming. In the zoom lens, one or more movable lens groups are set asnegative lens groups, and the configuration of the first lens group isappropriately set, such that the predetermined conditional expressionsare satisfied. With such a configuration, it is possible to provide azoom lens, which can be configured to have a small size while ensuring ahigh zoom ratio and has high optical performance by satisfactorilycorrecting chromatic aberration, and an imaging apparatus comprising thezoom lens.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a configuration of a zoomlens of Example 1 of the present invention.

FIG. 2 is a cross-sectional view illustrating rays and the configurationof the zoom lens shown in FIG. 1, where the upper part thereof shows thezoom lens in the wide-angle end state, the middle part thereof shows thezoom lens in the middle focal length state, and the lower part thereofshows the zoom lens in the telephoto end state.

FIG. 3 is a cross-sectional view illustrating a configuration of a zoomlens of Example 2 of the present invention.

FIG. 4 is a cross-sectional view illustrating a configuration of a zoomlens of Example 3 of the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of a zoomlens of Example 4 of the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of a zoomlens of Example 5 of the present invention.

FIG. 7 is a cross-sectional view illustrating a configuration of a zoomlens of Example 6 of the present invention.

FIG. 8 is a cross-sectional view illustrating a configuration of a zoomlens of Example 7 of the present invention.

FIG. 9 is a cross-sectional view illustrating a configuration of a zoomlens of Example 8 of the present invention.

FIG. 10 is a diagram of aberrations of the zoom lens according toExample 1 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 11 is a diagram of aberrations of the zoom lens according toExample 2 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 12 is a diagram of aberrations of the zoom lens according toExample 3 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 13 is a diagram of aberrations of the zoom lens according toExample 4 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 14 is a diagram of aberrations of the zoom lens according toExample 5 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 15 is a diagram of aberrations of the zoom lens according toExample 6 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 16 is a diagram of aberrations of the zoom lens according toExample 7 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 17 is a diagram of aberrations of the zoom lens according toExample 8 of the present invention, where the upper part thereof showsthe zoom lens in the wide-angle end state, the middle part thereof showsthe zoom lens in the middle focal length state, the lower part thereofshows the zoom lens in the telephoto end state, and aberration diagramsof each state are spherical aberration diagram, astigmatism diagram,distortion diagram, and lateral chromatic aberration diagram in orderfrom the left side.

FIG. 18 is a schematic configuration diagram of an imaging apparatusaccording to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to drawings. FIG. 1 is a cross-sectional view illustrating alens configuration of a zoom lens at the wide-angle end according to anembodiment of the present invention. FIG. 2 shows the lensconfigurations of the zoom lens shown in FIG. 1 and rays of eachconfiguration. In FIG. 2, the wide-angle end state is shown in the upperpart indicated by “WIDE”, and rays are shown as on-axis rays wa and rayswith the maximum angle of view wb. Further, the middle focal lengthstate is shown in the middle part indicated by “MIDDLE”, and rays areshown as on-axis rays ma and rays with the maximum angle of view mb. Inaddition, the telephoto end state is shown in the lower part indicatedby “TELE”, and rays are shown as on-axis rays to and rays with themaximum angle of view tb. The examples shown in FIGS. 1 and 2 correspondto the zoom lens of Example 1 to be described later. FIGS. 1 and 2 eachshow a state where the object at infinity is in focus, where the leftside of the drawing is the object side and the right side of the drawingis the image side. Hereinafter, description will be given mainly withreference to FIG. 1.

In order to mount the zoom lens on an imaging apparatus, it ispreferable to provide various filters and/or a protective cover glassbased on specification of the imaging apparatus. Thus, FIG. 1 shows anexample where an optical member PP, in which those are considered and ofwhich the incident surface and the exit surface are parallel, isdisposed between the lens system and the image plane Sim. However, aposition of the optical member PP is not limited to that shown in FIG.1, and it is also possible to adopt a configuration in which the opticalmember PP is omitted.

The zoom lens of the present embodiment substantially consists of, inorder from the object side along the optical axis Z: a first lens groupG1 that remains stationary with respect to an image plane Sim duringzooming and has a positive refractive power; a plurality of movable lensgroups that move by changing distances between groups adjacent to eachother in a direction of an optical axis during zooming; and a final lensgroup Ge that has a positive refractive power and remains stationarywith respect to the image plane Sim during zooming.

The zoom lens of an example shown in FIG. 1 substantially consists of,in order from the object side along the optical axis Z, the first lensgroup G1, a second lens group G2, a third lens group G3, and a fourthlens group G4. During zooming, the first lens group G1 and the fourthlens group G4 remain stationary with respect to the image plane Sim, andthe second lens group G2 and the third lens group G3 move by changing arelative distance therebetween in the direction of the optical axis. Inthe example shown in FIG. 1, the second lens group G2 and the third lensgroup G3 each correspond to the movable lens group, and the fourth lensgroup G4 corresponds to the final lens group Ge. In FIG. 1, under eachof the second lens group G2 and the third lens group G3, a direction ofmoving each lens group during zooming from the wide-angle end to thetelephoto end is schematically indicated by an arrow.

In the example shown in FIG. 1, the first lens group G1 consists ofeight lenses L11 to L18 in order from the object side. The second lensgroup G2 consists of four lenses L21 to L24 in order from the objectside. The third lens group G3 consists of two lenses L31 and L32 inorder from the object side. The fourth lens group G4 consists of ninelenses L41 to L49 in order from the object side. However, in the zoomlens of the present invention, the number of lenses composing each lensgroup is not necessarily limited to the example shown in FIG. 1.

FIG. 1 shows an example in which an aperture stop St is disposed betweenthe third lens group G3 and the fourth lens group G4, but the aperturestop St may be disposed at another position. Further, the aperture stopSt shown in FIG. 1 does not necessarily indicate its sizes and/orshapes, and indicates a position of the aperture stop St on the opticalaxis Z.

In the zoom lens of the present embodiment, by forming the first lensgroup G1 closest to the object side as a positive lens group, it ispossible to shorten the total length of the lens system, and thus thereis an advantage in reduction in size. By forming the final lens group Geclosest to the image side as the positive lens group, it is possible tosuppress an increase in incident angle of the principal ray of theoff-axis rays incident onto the image plane Sim. As a result, it ispossible to suppress shading. In addition, by adopting a configurationin which the lens group closest to the object side and the lens groupclosest to the image side remain stationary during zooming, it ispossible to make the total length of the lens system unchanged duringzooming.

The zoom lens is configured such that at least one movable lens groupamong the plurality of movable lens groups has a negative refractivepower. Thereby, it is possible to achieve a high zoom ratio.

The first lens group G1 has two or more positive lenses, and onepositive lens is disposed to be closest to the image side of the firstlens group G1. Hereinafter, the positive lens disposed to be closest tothe image side of the first lens group G1 is referred to as an imageside positive lens. This zoom lens is configured to satisfy all ofConditional Expressions (1) to (5) relating to the image side positivelens. Thereby, it is possible to satisfactorily correct chromaticaberration of the first lens group G1 while achieving reduction in sizeby minimizing the number of lenses of the first lens group G1. Inparticular, it is possible to satisfactorily correct longitudinalchromatic aberration on the telephoto side and chromatic aberrationcaused by the on-axis marginal ray in the first lens group G1. In thelens system described in JP2015-94866A described above, there is aproblem that the F number on the telephoto side increases because theon-axis marginal ray is shielded by using members other than theaperture stop on the telephoto side so as not to cause largelongitudinal chromatic aberration on the telephoto side. In contrast, itis possible to prevent occurrence of the problem according to the zoomlens of the present embodiment since it is possible to satisfactorilycorrect longitudinal chromatic aberration on the telephoto side.

0.25<fl/fz<0.7  (1)

55<νz<68  (2)

15<νmx−νz<50  (3)

2.395<Nz+0.012×νz  (4)

0.634<θgFz+0.001625×νz<0.647  (5)

Here, fl is a focal length of the first lens group,

fz is a focal length of the image side positive lens,

νz is an Abbe number of the image side positive lens at the d line,

νmx is an Abbe number of a positive lens, of which the Abbe number atthe d line is at a maximum value, among positive lenses disposed to becloser to the object side than the image side positive lens at the dline,

Nz is a refractive index of the image side positive lens at the d line,and

θgFz is a partial dispersion ratio of the image side positive lensbetween the g line and the F line.

By not allowing the result of Conditional Expression (1) to be equal toor less than the lower limit, it is possible to prevent longitudinalchromatic aberration from being excessively corrected, and particularly,it is possible to prevent longitudinal chromatic aberration on thetelephoto side from being excessively corrected. By not allowing theresult of Conditional Expression (1) to be equal to or greater than theupper limit, it is possible to prevent longitudinal chromatic aberrationfrom being insufficiently corrected, and particularly, it is possible toprevent longitudinal chromatic aberration on the telephoto side frombeing insufficiently corrected. In order to more enhance the effect ofConditional Expression (1), it is preferable that Conditional Expression(1-1) is satisfied.

0.35<fl/fz<0.65  (1-1)

By not allowing the result of Conditional Expression (2) to be equal toor less than the lower limit, it is possible to prevent lateralchromatic aberration on the wide-angle side from being insufficientlycorrected, and it is possible to prevent longitudinal chromaticaberration on the telephoto side from being insufficiently corrected. Bynot allowing the result of Conditional Expression (2) to be equal to orgreater than the upper limit, it is possible to prevent lateralchromatic aberration on the wide-angle side from being excessivelycorrected, and it is possible to prevent longitudinal chromaticaberration on the telephoto side from being excessively corrected. Inorder to more enhance the effect of Conditional Expression (2), it ispreferable that Conditional Expression (2-1) is satisfied.

56<νz<65  (2-1)

By not allowing the result of Conditional Expression (3) to be equal toor less than the lower limit, it is possible to prevent lateralchromatic aberration on the wide-angle side from being insufficientlycorrected, and it is possible to prevent longitudinal chromaticaberration on the telephoto side from being insufficiently corrected. Bynot allowing the result of Conditional Expression (3) to be equal to orgreater than the upper limit, it is possible to prevent lateralchromatic aberration on the wide-angle side from being excessivelycorrected, and it is possible to prevent longitudinal chromaticaberration on the telephoto side from being excessively corrected. Inorder to more enhance the effect of Conditional Expression (3), it ispreferable that Conditional Expression (3-1) is satisfied.

30<νmx−νz<45  (3-1)

By not allowing the result of Conditional Expression (4) to be equal toor less than the lower limit, it is possible to prevent lateralchromatic aberration on the wide-angle side from being insufficientlycorrected, and it is possible to prevent longitudinal chromaticaberration on the telephoto side from being insufficiently corrected.Further, it is preferable that the imaging lens satisfies ConditionalExpression (4-1). By not allowing the result of Conditional Expression(4-1) to be equal to or greater than the upper limit, it is possible toprevent lateral chromatic aberration on the wide-angle side from beingexcessively corrected, and it is possible to prevent longitudinalchromatic aberration on the telephoto side from being excessivelycorrected.

2.395<Nz+0.012×νz<2.455  (4-1)

By satisfying Conditional Expression (2) and by not allowing the resultof Conditional Expression (5) to be equal to or less than the lowerlimit, it is possible to prevent secondary spectrum from beingexcessively corrected. By satisfying Conditional Expression (2) and bynot allowing the result of Conditional Expression (5) to be equal to orgreater than the upper limit, it is possible to prevent secondaryspectrum from being insufficiently corrected.

It is preferable that the zoom lens satisfies Conditional Expression(6).

1.2<ft/fl<2.8  (6)

Here, ft is a focal length of the whole system at the telephoto end, and

fl is a focal length of the first lens group.

By not allowing the result of Conditional Expression (6) to be equal toor less than the lower limit, it is possible to prevent the refractivepower of the first lens group G1 from being excessively weak, and it ispossible to minimize the length of the first lens group G1 in thedirection of the optical axis. As a result, there is an advantage inreduction in size. By not allowing the result of Conditional Expression(6) to be equal to or greater than the upper limit, it is possible toprevent the refractive power of the first lens group G1 from beingexcessively strong. As a result, it becomes easy to correct aberrationsoccurring in the first lens group G1. In order to more enhance theeffect of Conditional Expression (6), it is preferable that ConditionalExpression (6-1) is satisfied.

1.5<ft/fl<20.5  (6-1)

It is preferable that the zoom lens satisfies Conditional Expression(7).

0.1<fw/fl<0.4  (7)

Here, fw is a focal length of the whole system at the wide-angle end,and fl is a focal length of the first lens group.

By not allowing the result of Conditional Expression (7) to be equal toor less than the lower limit, it is possible to prevent the refractivepower of the first lens group G1 from being excessively weak, and it ispossible to minimize the height of the off-axis rays from the opticalaxis Z. Therefore, it is possible to suppress an increase in size of thelens. By not allowing the result of Conditional Expression (7) to beequal to or greater than the upper limit, it is possible to prevent therefractive power of the first lens group G1 from being excessivelystrong. As a result, it becomes easy to correct aberrations occurring inthe first lens group G1. In order to more enhance the effect ofConditional Expression (7), it is preferable that Conditional Expression(7-1) is satisfied.

0.11<fw/fl<0.35  (7-1)

The zoom lens may be configured to perform focusing by moving one ormore lenses in the first lens group G1 in the direction of the opticalaxis. As described above, focusing is performed by using a lens closerto the object side than a lens group moving during zooming, and thus itbecomes easy to suppress the shift of focus during zooming.

For example, the first lens group G1 of the example shown in FIG. 1substantially consists of, in order from the object side, a first lensgroup front group G1 a that has a negative refractive power and remainsstationary with respect to the image plane Sim during focusing, a firstlens group intermediate group G1 b that has a positive refractive powerand moves in the direction of the optical axis during focusing, and afirst lens group rear group G1 c that is set such that a distance in thedirection of the optical axis between the first lens group rear group G1c and the first lens group intermediate group G1 b changes duringfocusing and has a positive refractive power. In a case of adopting sucha configuration, it becomes easy to suppress change in the angle of viewcaused by focusing. In FIG. 1, both arrows below the first lens groupintermediate group G1 b indicate that the first lens group intermediategroup G1 b is movable in the directions of the optical axis duringfocusing.

In addition, the first lens group rear group G1 c may remain stationarywith respect to the image plane Sim during focusing. In such a case, thelens groups, which move during focusing, can be composed of a number ofonly the first lens group intermediate group G1 b, and it is possible tosimplify the focusing mechanism. Thus, it is possible to suppress anincrease in size of the apparatus. Alternatively, the first lens grouprear group G1 c may move in the direction of the optical axis along alocus different from that of the first lens group intermediate group G1b during focusing. In such a case, it is possible to suppressfluctuation in aberration during focusing.

In a case where the first lens group G1 has the three lens groups, it ispreferable to satisfy Conditional Expression (8).

0.5<flc/fz<0.7  (8)

Here, flc is a focal length of the first lens group rear group, and

fz is a focal length of the image side positive lens.

By not allowing the result of Conditional Expression (8) to be equal toor less than the lower limit, it is possible to prevent longitudinalchromatic aberration from being excessively corrected, and particularly,it is possible to prevent longitudinal chromatic aberration on thetelephoto side from being excessively corrected. By not allowing theresult of Conditional Expression (8) to be equal to or greater than theupper limit, it is possible to prevent longitudinal chromatic aberrationfrom being insufficiently corrected, and particularly, it is possible toprevent longitudinal chromatic aberration on the telephoto side frombeing insufficiently corrected. In order to more enhance the effect ofConditional Expression (8), it is preferable that Conditional Expression(8-1) is satisfied.

0.55<flc/fz<0.68  (8-1)

In the case where the first lens group G1 has the three lens groups, itis preferable that the first lens group front group G1 a has at leastone negative lens that satisfies Conditional Expressions (9) and (10).In such a case, it is possible to reduce load of correction of chromaticaberration in the lens groups subsequent to the first lens group frontlens group G1 a. As a result, it is possible to satisfactorily correctchromatic aberration of the first lens group G1.

55<νn  (9)

0.635<θgFn+0.001625×νn<0.675  (10)

Here, νn is an Abbe number of the negative lens of the first lens groupfront group at the d line, and

θgFn is a partial dispersion ratio of the negative lens of the firstlens group front group between the g line and the F line.

By not allowing the result of Conditional Expression (9) to be equal toor less than the lower limit, it is possible to satisfactorily correctlateral chromatic aberration on the wide-angle side and longitudinalchromatic aberration on the telephoto side. Further, it is preferablethat the imaging lens satisfies Conditional Expression (9-1). In a casewhere the result of Conditional Expression (9-1) is equal to or greaterthan the upper limit, only the material having a low refractive indexcan be selected within the range of the existing optical material. As aresult, it is difficult to ensure the negative refractive powernecessary for achieving the wide angle in the first lens group frontgroup G1 a. By not allowing the result of Conditional Expression (9-1)to be equal to or greater than the upper limit, it is possible to avoidsuch a problem.

55<νn<80  (9-1)

By satisfying Conditional Expression (9) and by not allowing the resultof Conditional Expression (10) to be equal to or less than the lowerlimit, it is possible to prevent secondary spectrum from beinginsufficiently corrected. By satisfying Conditional Expression (9) andby not allowing the result of Conditional Expression (10) to be equal toor greater than the upper limit, it is possible to prevent secondaryspectrum from being excessively corrected. In order to more enhance theeffect of Conditional Expression (10), it is preferable that ConditionalExpression (10-1) is satisfied.

0.635<θgFn+0.001625×νn<0.665  (10-1)

The first lens group front group G1 a may be configured to have,successively in order from a position closest to the object side, anegative meniscus lens concave toward an image side, and a negative lensconcave toward the object side. In such a case, it is possible to obtaina negative refractive power necessary for achieving wide angle whilesuppressing occurrence of astigmatism. The lens closest to the imageside in the first lens group front group G1 a may be a positive meniscuslens concave toward the image side. In such a case, it is possible tosuppress occurrence of astigmatism on the wide-angle side. Further, itis also possible to satisfactorily correct spherical aberration, whichis generated by the first lens group front group G1 a and has an overtendency on the telephoto side, particularly spherical aberration havinga high order which is 5th order or more. As in the example of FIG. 1,the first lens group front group G1 a consists of, in order from theobject side, a negative meniscus lens, a negative lens, and a positivemeniscus lens. These three lenses may be single lenses which are notentirely cemented. In such a case, it is possible to obtain a negativerefractive power necessary for achieving wide angle while achievingreduction in size and suppressing occurrence of astigmatism.

It is preferable that the first lens group rear group G1 c has,successively in order from the object side, a cemented lens, in which anegative lens and a positive lens are cemented in order from the objectside, and a positive lens. In such a case, it becomes easy to correctchromatic aberration of the first lens group G1 and correct sphericalaberration on the telephoto side. In addition, in the case where thefirst lens group rear group G1 c is configured to consist of, in orderfrom the object side, a cemented lens, in which a negative lens and apositive lens are cemented in order from the object side, and a positivelens, it is possible to easily correct chromatic aberration of the firstlens group G1 and correct spherical aberration on the telephoto sidewhile achieving reduction in size.

Next, the plurality of movable lens groups will be described. In thisplurality of movable lens groups, it is preferable that the movable lensgroup closest to the image side has a negative refractive power. In sucha case, the movement stroke of the movable lens group located closer tothe object side than the movable lens group closest to the image sidecan be set to be longer while minimizing the total length of the lenssystem. Thus, there is an advantage in achieving reduction in size andhigh zoom ratio.

In the example shown in FIG. 1, the number of plural movable lens groupsarranged between the first lens group G1 and the final lens group Ge istwo, and these two movable lens groups also have negative refractivepowers. In such a case, it is possible to realize a zoom lens having asmall size and a high zoom ratio while simplifying the mechanism. Thenumber of plural movable lens groups arranged between the first lensgroup G1 and the final lens group Ge may be three or more. For example,the plurality of movable lens groups may be configured to substantiallyconsist of, in order from the object side, a lens group having apositive refractive power, a lens group having a negative refractivepower, and a lens group having a negative refractive power. In such acase, it is possible to realize a zoom lens having a small size and ahigh zoom ratio while suppressing occurrence of distortion on thewide-angle side and/or spherical aberration on the telephoto side.Alternatively, the plurality of movable lens groups may be configured tosubstantially consist of, in order from the object side, a lens grouphaving a negative refractive power, a lens group having a positiverefractive power, and a lens group having a negative refractive power.In such a case, aberrations are easily corrected, and a zoom lens havinga small size and a high zoom ratio can be realized.

The above-mentioned preferred configurations and/or availableconfigurations each may be any combination, and it is preferable toappropriately selectively adopt the configuration in accordance withdemands for the zoom lens. By appropriately adopting the configuration,it is possible to realize more favorable optical system. According tothe present embodiment, it is possible to realize a zoom lens, which hasa small size while ensuring a high zoom ratio and has high opticalperformance by satisfactorily correcting chromatic aberration. It shouldbe noted that the high zoom ratio described herein means 5.5 times ormore.

Next, numerical examples of the zoom lens of the present invention willbe described.

Example 1

A lens configuration of a zoom lens of Example 1 is shown in FIGS. 1 and2, and an illustration method thereof is as described above. Therefore,repeated description is partially omitted herein. The zoom lens ofExample 1 consists of, in order from the object side, a first lens groupG1, a second lens group G2, a third lens group G3, an aperture stop St,and a fourth lens group G4. In these four lens groups, the distances inthe direction of the optical axis between groups adjacent to each otherchange during zooming. Both the second lens group G2 and the third lensgroup G3 are movable lens groups having negative refractive powers. Thefirst lens group G1 consists of, in order from the object side, a firstlens group front group G1 a that consists of three lenses and has anegative refractive power, a first lens group intermediate group G1 bthat consists of two lenses and has a positive refractive power, and afirst lens group rear group G1 c that consists of three lenses and has apositive refractive power. During focusing, the first lens group frontgroup G1 a remains stationary with respect to the image plane Sim, thefirst lens group intermediate group G1 b moves, and the distance in thedirection of the optical axis between the first lens group intermediategroup G1 b and the first lens group rear group G1 c changes.

Table 1 shows basic lens data of the zoom lens of Example 1, Table 2shows values of specification and variable surface distances, and Table3 shows aspheric coefficients thereof. In Table 1, the column of Sishows a surface number i (i=1, 2, 3, . . . ) attached to an i-th surfaceof the elements, where i sequentially increases toward the image side ina case where an object side surface of an element closest to the objectside is regarded as a first surface. The column of Ri shows a radius ofcurvature of the i-th surface. The column of Di shows a distance on theoptical axis Z between the i-th surface and an (i+1)th surface. In Table1, the column of Ndj shows a refractive index of a j-th (j=1, 2, 3, . .. ) element at the d line (a wavelength of 587.6 nm), where jsequentially increases toward the image side in a case where the elementclosest to the object side is regarded as the first element. The columnof vdj shows an Abbe number of the j-th element at the d line. Thecolumn of θgFj shows a partial dispersion ratio of the j-th elementbetween the g line and the F line.

Here, reference signs of radii of curvature of surface shapes convextoward the object side are set to be positive, and reference signs ofradii of curvature of surface shapes convex toward the image side areset to be negative. Table 1 additionally shows the aperture stop St andthe optical member PP. In Table 1, in a place of a surface number of asurface corresponding to the aperture stop St, the surface number and aterm of (St) are noted. A value at the bottom place of Di indicates adistance between the image plane Sim and the surface closest to theimage side in the table. In Table 1, the variable surface distances,which are variable during zooming, are referenced by the reference signsDD[ ], and are written into places of Di, where object side surfacenumbers of distances are noted in [ ].

In Table 2, values of the zoom ratio Zr, the focal length f of the wholesystem, the back focal length Bf in terms of the air conversiondistance, the F number FNo., the maximum total angle of view 2ω, andvariable surface distance are based on the d line. (°) in the place of2ω indicates that the unit thereof is a degree. In Table 2, values inthe wide-angle end state, the middle focal length state, and thetelephoto end state are respectively shown in the columns labeled byWIDE, MIDDLE, and TELE. The values of Tables 1 and 2 are values in astate where the object at infinity is in focus.

In Table 1, the reference sign * is attached to surface numbers ofaspheric surfaces, and numerical values of the paraxial radius ofcurvature are written into the column of the radius of curvature of theaspheric surface. Table 3 shows aspheric coefficients of the asphericsurfaces of Example 1. The “E−n” (n: an integer) in numerical values ofthe aspheric coefficients of Table 3 indicates “×10−n”. The asphericcoefficients are values of the coefficients KA and Am (m=3, 4, 5, . . .20) in aspheric surface expression represented as the followingexpression.

$\begin{matrix}{{Zd} = {\frac{C \times h^{2}}{1 + \sqrt{1 - {{KA} \times C^{2} \times h^{2}}}} + {\underset{m}{\Sigma}{Am} \times h^{m}}}} & {{Numerical}\mspace{14mu} {Expression}\mspace{14mu} 1}\end{matrix}$

Here, Zd is an aspheric surface depth (a length of a perpendicular froma point on an aspheric surface at height h to a plane that isperpendicular to the optical axis that contacts with the vertex of theaspheric surface),

h is a height (a length of a perpendicular, which is in a planeperpendicular to the optical axis that contacts with the vertex of theaspheric surface, from the point on the aspheric surface to the opticalaxis),

C is a paraxial curvature, and

KA and Am are aspheric coefficients.

In data of each table, a degree is used as a unit of an angle, andmillimeter (mm) is used as a unit of a length, but appropriate differentunits may be used since the optical system can be used even in a casewhere the system is enlarged or reduced in proportion. Further, each ofthe following tables shows numerical values rounded off to predetermineddecimal places.

TABLE 1 Example 1 Si Ri Di Ndj νdj θgFj  1 370.38276 2.53000 1.77249949.60 0.5521  2 57.75739 26.80621  3 −152.87368 2.20000 1.695602 59.050.5435  4 486.73340 0.39000  5 103.42182 4.56107 1.892860 20.36 0.6394 6 194.06007 6.98917  7 ∞ 6.83489 1.438750 94.66 0.5340  8 −128.102020.12000  9 371.48362 5.66802 1.438750 94.66 0.5340  10 −249.304749.12857  11 93.94676 2.19983 1.846660 23.88 0.6218  12 56.39558 16.026341.438750 94.66 0.5340  13 −130.65476 0.12000  14 72.96983 5.845761.695602 59.05 0.5435  15 264.75541 DD[15] *16 47.39581 1.38000 1.85400040.38 0.5689  17 23.64140 7.04442  18 −51.14856 1.04910 1.632460 63.770.5421  19 38.48116 5.84592  20 44.54062 5.58518 1.592701 35.31 0.5934 21 −55.99669 1.05000 1.592824 68.62 0.5441  22 −270.02836 DD[22]  23−39.56418 1.05000 1.632460 63.77 0.5421  24 44.13413 4.04616 1.62588235.70 0.5893  25 −177.97071 DD[25]  26 (St) ∞ 1.52068  27 134.913983.33963 1.916500 31.60 0.5912  28 −85.19407 0.20018  29 30.90160 8.076311.496999 81.54 0.5375  30 −41.69367 1.89903 1.910823 35.25 0.5822  3185.64653 5.33750  32 36.30103 6.58324 1.749497 35.28 0.5870  33−105.50860 0.99910  34 138.71124 1.10000 1.900433 37.37 0.5772  3518.11707 9.50941 1.632460 63.77 0.5421  36 −111.49284 0.11910  3739.11125 8.33426 1.438750 94.66 0.5340  38 −24.02071 2.00090 1.95374832.32 0.5901  39 27.28562 18.99884  40 48.65552 4.69458 1.720467 34.710.5835  41 −182.07198 0.00000  42 ∞ 2.30000 1.516330 64.14 0.5353  43 ∞34.04250

TABLE 2 Example 1 WIDE MIDDLE TELE Zr 1.00 2.90 5.79 f 20.45 59.31118.42 Bf 35.56 35.56 35.56 FNo. 3.32 3.32 3.32 2ω (°) 72.32 26.30 13.50DD[15] 1.54 42.02 57.17 DD[22] 47.88 7.36 5.49 DD[25] 14.71 14.75 1.47

TABLE 3 Example 1 Surface Number 16 KA 1.0000000E+00 A3 −1.4481371E−20A4 −2.2097151E−06 A5 1.1906712E−06 A6 −2.1344004E−07 A7 1.2774506E−08 A81.1294113E−09 A9 −2.3286340E−10 A10 1.4115083E−11 A11 4.6903088E−13 A12−1.7545649E−13 A13 9.6716937E−15 A14 6.5945061E−16 A15 −7.7270143E−17A16 −2.4667346E−19 A17 2.3248734E−19 A18 −4.1986679E−21 A19−2.5896844E−22 A20 7.5912487E−24

FIG. 10 shows aberration diagrams in a state where an object at infinityis brought into focus through the zoom lens of Example 1. In order fromthe left side of FIG. 10, spherical aberration, astigmatism, distortion,and lateral chromatic aberration (lateral chromatic aberration) areshown. In FIG. 10, the upper part labeled by WIDE shows the zoom lens inthe wide-angle end state, the middle part labeled by MIDDLE shows thezoom lens in the middle focal length state, the lower part labeled byTELE shows the zoom lens in the telephoto end state. In the sphericalaberration diagram, aberrations at the d line (a wavelength of 587.6nm), the C line (a wavelength of 656.3 nm), the F line (a wavelength of486.1 nm), and the g line (a wavelength of 435.8 nm) are respectivelyindicated by the black solid line, the long dashed line, the chain line,and the gray solid line. In the astigmatism diagram, aberration in thesagittal direction at the d line is indicated by the solid line, andaberration in the tangential direction at the d line is indicated by theshort dashed line. In the distortion diagram, aberration at the d lineis indicated by the solid line. In the lateral chromatic aberrationdiagram, aberrations at the C line, the F line, and the g line arerespectively indicated by the long dashed line, the chain line, and thegray solid line. In the spherical aberration diagram, FNo. indicates anF number. In the other aberration diagrams, co indicates a half angle ofview.

In the description of Example 1, reference signs, meanings, anddescription methods of the respective data pieces are the same as thosein the following examples unless otherwise noted. Therefore, in thefollowing description, repeated description will be omitted.

Example 2

FIG. 3 is a cross-sectional view of a zoom lens of Example 2. The zoomlens of Example 2 consists of, in order from the object side, a firstlens group G1, a second lens group G2, a third lens group G3, anaperture stop St, and a fourth lens group G4. The first lens group G1consists of, in order from the object side, a first lens group frontgroup G1 a consisting of three lenses, a first lens group intermediategroup G1 b consisting of two lenses, and a first lens group rear groupG1 c consisting of three lenses. The present example is the same asExample 1 in terms of the signs of refractive powers of the lens groups,the lens groups moving during zooming, and the lens groups moving duringfocusing.

Table 4 shows basic lens data of the zoom lens of Example 2, Table 5shows values of specification and variable surface distances, Table 6shows aspheric coefficients, and FIG. 11 shows aberration diagrams in astate where the object at infinity is in focus.

TABLE 4 Example 2 Si Ri Di Ndj νdj θgFj  1 91.92719 2.53098 1.77249949.60 0.5521  2 47.04979 22.24446  3 −170.66128 2.20000 1.632460 63.770.5421  4 206.04456 0.38503  5 71.99393 4.45167 1.892860 20.36 0.6394  6102.54612 6.82807  7 196.27328 2.20005 1.772499 49.60 0.5521  8103.84467 11.12110 1.438750 94.66 0.5340  9 −171.05234 14.89014  1096.08666 2.19923 1.854780 24.80 0.6123  11 58.74401 15.93330 1.43875094.66 0.5340  12 −103.69633 0.12000  13 75.26293 6.27475 1.695602 59.050.5435  14 827.30524 DD[14] *15 72.65286 1.38000 1.854000 40.38 0.5689 16 25.93821 6.72575  17 −41.69691 1.05070 1.592824 68.62 0.5441  1837.57713 4.48600  19 44.63168 5.32952 1.592701 35.31 0.5934  20−52.52729 1.05090 1.592824 68.62 0.5441  21 −121.55768 DD[21]  22−42.05800 1.04975 1.632460 63.77 0.5421  23 39.59542 4.12871 1.62588235.70 0.5893  24 −246.96103 DD[24]  25 (St) ∞ 1.39983  26 140.447903.12682 1.916500 31.60 0.5912  27 −89.38492 0.20011  28 28.98877 8.219541.496999 81.54 0.5375  29 −42.61188 1.10000 1.910823 35.25 0.5822  3090.28815 5.81177  31 39.25421 6.59993 1.749497 35.28 0.5870  32−89.09971 1.37631  33 139.77728 1.13913 1.900433 37.37 0.5772  3417.41563 9.99924 1.695602 59.05 0.5435  35 −724.38203 0.12001  3629.98468 6.67820 1.438750 94.66 0.5340  37 −24.61428 2.00000 1.95374832.32 0.5901  38 25.83563 20.39478  39 47.76648 5.13049 1.720467 34.710.5835  40 −176.41808 0.00000  41 ∞ 2.30000 1.516330 64.14 0.5353  42 ∞34.52368

TABLE 5 Example 2 WIDE MIDDLE TELE Zr 1.00 2.90 5.79 f 20.62 59.81119.41 Bf 36.04 36.04 36.04 FNo. 3.31 3.31 3.30 2ω (°) 71.86 26.08 13.40DD[14] 1.00 41.46 56.83 DD[21] 49.91 8.08 4.34 DD[24] 12.04 13.41 1.78

TABLE 6 Example 2 Surface Number 15 KA 1.0000000E+00 A3 0.0000000E+00 A4−7.0268357E−07 A5 −2.8254006E−07 A6 1.9442811E−07 A7 −1.0869783E−08 A8−6.5332158E−09 A9 1.0648429E−09 A10 8.0520025E−12 A11 −1.2814263E−11 A126.6704958E−13 A13 5.0970812E−14 A14 −5.3557213E−15 A15 −3.0887770E−18A16 1.5245419E−17 A17 −4.1575720E−19 A18 −1.2158029E−20 A196.9438881E−22 A20 −8.1994339E−24

Example 3

FIG. 4 is a cross-sectional view of a zoom lens of Example 3. The zoomlens of Example 3 consists of, in order from the object side, a firstlens group G1, a second lens group G2, a third lens group G3, anaperture stop St, and a fourth lens group G4. The first lens group G1consists of, in order from the object side, a first lens group frontgroup G1 a consisting of three lenses, a first lens group intermediategroup G1 b consisting of two lenses, and a first lens group rear groupG1 c consisting of three lenses. The present example is the same asExample 1 in terms of the signs of refractive powers of the lens groups,the lens groups moving during zooming, and the lens groups moving duringfocusing.

Table 7 shows basic lens data of the zoom lens of Example 3, Table 8shows values of specification and variable surface distances, Table 9shows aspheric coefficients, and FIG. 12 shows aberration diagrams in astate where the object at infinity is in focus.

TABLE 7 Example 3 Si Ri Di Ndj νdj θgFj  1 179.73060 2.80000 1.88299740.76 0.5668  2 57.51902 19.98932  3 −182.56446 2.20000 1.632460 63.770.5421  4 156.29712 1.00000  5 89.75457 4.58961 1.922860 18.90 0.6496  6161.94294 6.83969  7 227.04433 2.20000 1.693717 42.53 0.5721  8104.53646 13.56898 1.438750 94.66 0.5340  9 −104.79903 8.44249  1088.91022 2.20000 1.805181 25.42 0.6162  11 56.35834 14.33676 1.43875094.66 0.5340  12 −212.00944 0.57436  13 90.10716 6.95580 1.695602 59.050.5435  14 −750.39403 DD [14] *15 59.64397 1.20000 1.902700 31.00 0.5943 16 28.07287 6.22761  17 −55.23848 1.20000 1.632460 63.77 0.5421  1839.20503 5.53307  19 46.62148 6.58080 1.592701 35.31 0.5934  20−34.36365 1.20000 1.592824 68.62 0.5441  21 −260.67806 DD [21]  22−44.46367 1.20000 1.632460 63.77 0.5421  23 64.72532 2.94300 1.62588235.70 0.5893  24 −221.99664 DD [24]  25 (St) ∞ 1.60000  26 225.293532.92131 1.916500 31.60 0.5912  27 −75.69537 0.12000  28 33.19063 7.431921.496999 81.54 0.5375  29 −42.89577 1.50000 1.918781 36.12 0.5784  30127.40865 6.99461  31 40.56322 7.82296 1.749497 35.28 0.5870  32−113.63622 1.00008  33 166.07425 1.50000 1.900433 37.37 0.5772  3418.91770 6.77468 1.695602 59.05 0.5435  35 −143.93112 1.23445  3638.97329 8.62046 1.438750 94.66 0.5340  37 −28.03994 2.00000 1.95374832.32 0.5901  38 24.50898 22.08922  39 43.14369 5.29015 1.628270 44.120.5704  40 −162.61439 0.00000  41 ∞ 2.30000 1.516330 64.14 0.5353  42 ∞31.88502

TABLE 8 Example 3 WIDE MIDDLE TELE Zr 1.00 2.90 5.79 f 20.71 60.06119.92 Bf 33.40 33.40 33.40 FNo. 3.30 3.31 3.30 2ω (°) 71.42 25.92 13.34DD [14] 1.05 45.79 62.89 DD [21] 54.63 8.29 4.17 DD [24] 13.18 14.781.80

TABLE 9 Example 3 Surface Number 15 KA 1.0000000E+00 A4 −5.4302541E−07A6 2.3244121E−08 A8 −4.3760338E−10 A10 4.9556187E−12 A12 −3.5362900E−14A14 1.5550030E−16 A16 −3.9877943E−19 A18 5.2706205E−22 A20−2.5738294E−25

Example 4

FIG. 5 is a cross-sectional view of a zoom lens of Example 4. The zoomlens of Example 4 consists of, in order from the object side, a firstlens group G1, a second lens group G2, a third lens group G3, anaperture stop St, and a fourth lens group G4. The first lens group G1consists of, in order from the object side, a first lens group frontgroup G1 a consisting of three lenses, a first lens group intermediategroup G1 b consisting of one lens, and a first lens group rear group G1c consisting of three lenses. The present example is the same as Example1 in terms of the signs of refractive powers of the lens groups, thelens groups moving during zooming, and the lens groups moving duringfocusing.

Table 10 shows basic lens data of the zoom lens of Example 4, Table 11shows values of specification and variable surface distances, Table 12shows aspheric coefficients, and FIG. 13 shows aberration diagrams in astate where the object at infinity is in focus.

TABLE 10 Example 4 Si Ri Di Ndj νdj θgFj  1 89.55061 2.53098 1.77249949.60 0.5521  2 46.20108 26.48567  3 −170.63384 2.20059 1.695602 59.050.5435  4 232.43449 0.39804  5 72.57068 4.47015 1.892860 20.36 0.6394  6106.19898 9.28374  7 2685.83228 5.32667 1.438750 94.66 0.5340  8−153.59919 14.66212  9 113.63731 2.16853 1.854780 24.80 0.6123  1059.63066 15.98231 1.438750 94.66 0.5340  11 −90.12780 0.14311  1270.15326 7.22393 1.695602 59.05 0.5435  13 661.14022 DD [13] *1452.60017 1.38000 1.854000 40.38 0.5689  15 24.43846 7.35169  16−41.94664 1.05070 1.592824 68.62 0.5441  17 37.98271 4.32904  1843.08412 5.54251 1.592701 35.31 0.5934  19 −50.53315 1.05090 1.59282468.62 0.5441  20 −188.16409 DD [20]  21 −40.22044 1.05085 1.632460 63.770.5421  22 45.33398 3.77263 1.625882 35.70 0.5893  23 −236.50416 DD [23] 24 (St) ∞ 1.40031  25 167.28051 3.05237 1.916500 31.60 0.5912  26−82.28668 0.20010  27 29.42802 8.35992 1.496999 81.54 0.5375  28−39.92973 1.11193 1.910823 35.25 0.5822  29 109.93898 5.82991  3040.35878 6.58497 1.749497 35.28 0.5870  31 −84.78434 1.14152  32135.35453 1.80010 1.900433 37.37 0.5772  33 17.94607 9.53921 1.69560259.05 0.5435  34 −613.17875 0.38246  35 30.56287 6.55776 1.438750 94.660.5340  36 −23.83965 1.99868 1.953748 32.32 0.5901  37 25.94805 19.72576 38 46.63103 4.99544 1.720467 34.71 0.5835  39 −193.04666 0.00000  40 ∞2.30000 1.516330 64.14 0.5353  41 ∞ 33.97254

TABLE 11 Example 4 WIDE MIDDLE TELE Zr 1.00 2.90 5.79 f 20.40 59.15118.09 Bf 35.49 35.49 35.49 FNo. 3.31 3.31 3.30 2ω (°) 72.42 26.38 13.56DD [13] 0.41 41.66 57.48 DD [20] 51.15 8.62 3.96 DD [23] 10.75 12.040.88

TABLE 12 Example 4 Surface Number 14 KA 1.0000000E+00 A3 0.0000000E+00A4 −7.0268357E−07 A5 −2.8254006E−07 A6 1.9442811E−07 A7 −1.0869783E−08A8 −6.5332158E−09 A9 1.0648429E−09 A10 8.0520025E−12 A11 −1.2814263E−11A12 6.6704958E−13 A13 5.0970812E−14 A14 −5.3557213E−15 A15−3.0887770E−18 A16 1.5245419E−17 A17 −4.1575720E−19 A18 −1.2158029E−20A19 6.9438881E−22 A20 −8.1994339E−24

Example 5

FIG. 6 is a cross-sectional view of a zoom lens of Example 5. The zoomlens of Example 5 consists of, in order from the object side, a firstlens group G1, a second lens group G2, a third lens group G3, a fourthlens group G4, an aperture stop St, and a fifth lens group G5. In thesefive lens groups, the distances in the direction of the optical axisbetween groups adjacent to each other change during zooming. The secondlens group G2 has a positive refractive power, the third lens group G3has a negative refractive power, and the fourth lens group G4 has anegative refractive power. The three lens groups including the second tofourth lens groups G2 to G4 are respectively movable lens groups. Thefirst lens group G1 consists of, in order from the object side, a firstlens group front group G1 a consisting of three lenses, a first lensgroup intermediate group G1 b consisting of two lenses, and a first lensgroup rear group G1 c consisting of three lenses. The signs of therefractive powers of three lens groups composing the first lens group G1and the lens groups moving during focusing are the same as that ofExample 1.

Table 13 shows basic lens data of the zoom lens of Example 5, Table 14shows values of specification and variable surface distances, and FIG.14 shows aberration diagrams in a state where the infinite object is infocus.

TABLE 13 Example 5 Si Ri Di Ndj νdj θgFj  1 351.51134 2.53000 1.77249949.60 0.5521  2 58.96679 25.71058  3 −165.96934 2.60041 1.695602 59.050.5435  4 438.51863 0.38517  5 96.24927 3.97797 1.892860 20.36 0.6394  6152.74199 7.45066  7 ∞ 7.63521 1.438750 94.66 0.5340  8 −131.920760.12000  9 409.13255 5.76407 1.438750 94.66 0.5340 10 −220.57814 7.9929011 108.72751 2.20000 1.755199 27.51 0.6103 12 55.83386 14.41684 1.43875094.66 0.5340 13 −168.55158 0.12000 14 73.70666 6.42934 1.632460 63.770.5421 15 597.12639 DD [15] 16 137.71857 2.63139 1.496999 81.54 0.537517 −1305.73558 DD [17] 18 87.40326 1.38000 1.834807 42.72 0.5649 1930.33959 6.29623 20 −51.31471 1.05000 1.695602 59.05 0.5435 21 48.761358.19661 22 68.58699 3.87635 1.698947 30.13 0.6030 23 −74.53716 1.060001.695602 59.05 0.5435 24 −291.58007 DD [24] 25 −41.67152 1.050551.632460 63.77 0.5421 26 53.61308 3.93485 1.625882 35.70 0.5893 27−158.08561 DD [27] 28 (St) ∞ 1.72135 29 112.40514 3.36815 1.916500 31.600.5912 30 −107.74797 0.20079 31 32.65637 7.66863 1.496999 81.54 0.537532 −44.13940 1.10000 1.910823 35.25 0.5822 33 146.04040 11.71151 3488.13789 3.58259 1.749497 35.28 0.5870 35 −61.95479 0.99901 36 81.548481.10000 1.900433 37.37 0.5772 37 20.55629 4.91890 1.632460 63.77 0.542138 122.56273 0.12011 39 27.72661 9.31235 1.438750 94.66 0.5340 40−30.83758 1.99952 1.953748 32.32 0.5901 41 28.75987 20.68485 42 49.858854.26967 1.720467 34.71 0.5835 43 −342.76867 0.00000 44 ∞ 2.300001.516330 64.14 0.5353 45 ∞ 33.79607

TABLE 14 Example 5 WIDE MIDDLE TELE Zr 1.00 2.90 5.79 f 20.84 60.43120.65 Bf 35.31 35.31 35.31 FNo. 3.31 3.31 3.31 2ω (°) 71.32 25.74 13.20DD [15] 0.15 24.27 35.03 DD [17] 1.00 14.99 18.97 DD [24] 37.14 3.288.30 DD [27] 25.73 21.48 1.71

Example 6

FIG. 7 is a cross-sectional view of a zoom lens of Example 6. The zoomlens of Example 6 consists of, in order from the object side, a firstlens group G1, a second lens group G2, a third lens group G3, a fourthlens group G4, an aperture stop St, and a fifth lens group G5. The firstlens group G1 consists of, in order from the object side, a first lensgroup front group G1 a consisting of three lenses, a first lens groupintermediate group G1 b consisting of two lenses, and a first lens grouprear group G1 c consisting of three lenses. The present example is thesame as Example 5 in terms of the signs of refractive powers of the lensgroups, the lens groups moving during zooming, and the lens groupsmoving during focusing.

Table 15 shows basic lens data of the zoom lens of Example 6, Table 16shows values of specification and variable surface distances, and FIG.15 shows aberration diagrams in a state where the infinite object is infocus.

TABLE 15 Example 6 Si Ri Di Ndj νdj θgFj  1 141.52029 2.53000 1.77249949.60 0.5521  2 52.25093 21.72306  3 −169.76115 2.60000 1.695602 59.050.5435  4 227.38169 0.38500  5 82.77517 4.42635 1.892860 20.36 0.6394  6124.35002 8.58347  7 327.66786 2.00000 1.755199 27.51 0.6103  8118.32799 14.02000 1.496999 81.54 0.5375  9 −110.23986 9.77811 10106.66417 2.22000 1.592701 35.31 0.5934 11 53.48612 16.28831 1.43875094.66 0.5340 12 −149.79662 0.12001 13 82.59842 6.25291 1.695602 59.050.5435 14 756.00928 DD [14] 15 336.83164 2.18103 1.496999 81.54 0.537516 −474.99451 DD [16] 17 92.73731 1.38000 1.882997 40.76 0.5668 1831.26761 6.12521 19 −41.83728 1.05000 1.695602 59.05 0.5435 20 50.598774.82631 21 62.85436 4.13921 1.698947 30.13 0.6030 22 −71.03230 1.060031.695602 59.05 0.5435 23 −133.54667 DD [23] 24 −39.50225 1.049101.632460 63.77 0.5421 25 33.98929 4.61700 1.625882 35.70 0.5893 26−303.50782 DD [26] 27 (St) ∞ 1.40000 28 81.21019 3.54813 1.916500 31.600.5912 29 −126.01058 0.19910 30 30.62497 8.16831 1.496999 81.54 0.537531 −38.67212 1.10094 1.910823 35.25 0.5822 32 149.32004 9.64313 33224495.80575 3.55897 1.749497 35.28 0.5870 34 −44.18529 1.00088 3532.84667 1.10000 1.900433 37.37 0.5772 36 16.11826 5.42939 1.63246063.77 0.5421 37 44.78303 0.12000 38 25.73387 7.06096 1.438750 94.660.5340 39 −28.99748 2.00000 1.953748 32.32 0.5901 40 32.42687 22.3471341 46.93465 4.05539 1.720467 34.71 0.5835 42 843.22322 0.00000 43 ∞2.30000 1.516330 64.14 0.5353 44 ∞ 35.59573

TABLE 16 Example 6 WIDE MIDDLE TELE Zr 1.00 2.90 5.79 f 20.81 60.36120.52 Bf 37.11 37.11 37.11 FNo. 3.31 3.31 3.31 2ω (°) 71.30 25.82 13.26DD [14] 1.00 27.09 39.25 DD [16] 1.00 15.00 18.97 DD [23] 46.61 7.173.58 DD [26] 15.08 14.43 1.89

Example 7

FIG. 8 is a cross-sectional view of a zoom lens of Example 7. The zoomlens of Example 7 consists of, in order from the object side, a firstlens group G1, a second lens group G2, a third lens group G3, a fourthlens group G4, an aperture stop St, and a fifth lens group G5. In thesefive lens groups, the distances in the direction of the optical axisbetween groups adjacent to each other change during zooming. The secondlens group G2 has a negative refractive power, the third lens group G3has a positive refractive power, and the fourth lens group G4 has anegative refractive power. The three lens groups including the second tofourth lens groups G2 to G4 are respectively movable lens groups. Thefirst lens group G1 consists of, in order from the object side, a firstlens group front group G1 a consisting of three lenses, a first lensgroup intermediate group G1 b consisting of two lenses, and a first lensgroup rear group G1 c consisting of three lenses. The signs of therefractive powers of three lens groups composing the first lens group G1and the lens groups moving during focusing are the same as that ofExample 1.

Table 17 shows basic lens data of the zoom lens of Example 7, Table 18shows values of specification and variable surface distances, Table 19shows aspheric coefficients, and FIG. 16 shows aberration diagrams in astate where the object at infinity is in focus.

TABLE 17 Example 7 Si Ri Di Ndj νdj θgFj  1 271.02397 2.53000 1.77249949.60 0.5521  2 53.66770 23.14907  3 −176.86065 2.20000 1.695602 59.050.5435  4 430.29449 0.39000  5 90.80833 5.23373 1.892860 20.36 0.6394  6172.69777 7.52493  7 ∞ 5.76344 1.438750 94.66 0.5340  8 −157.361290.12000  9 432.45221 4.57630 1.438750 94.66 0.5340  10 −351.9692511.77482  11 105.41212 2.19983 1.846660 23.88 0.6218  12 57.9153516.99595 1.438750 94.66 0.5340  13 −102.71103 0.12000  14 68.911166.18166 1.695602 59.05 0.5435  15 251.51097 DD [15] *16 48.87312 1.380001.854000 40.38 0.5689  17 23.92316 6.92527  18 −51.61678 1.049101.632460 63.77 0.5421  19 37.81667 DD [19]  20 45.09991 5.27163 1.59270135.31 0.5934  21 −57.23178 1.05000 1.592824 68.62 0.5441  22 −271.05488DD [22]  23 −42.52742 1.05000 1.632460 63.77 0.5421  24 52.07641 3.852631.625882 35.70 0.5893  25 −137.87042 DD [25]  26 (St) ∞ 1.47098  27125.78267 3.21681 1.916500 31.60 0.5912  28 −97.17131 0.20021  2930.88167 7.64434 1.496999 81.54 0.5375  30 −44.27610 1.10005 1.91082335.25 0.5822  31 79.59338 5.66259  32 38.09474 6.60000 1.749497 35.280.5870  33 −103.42350 0.99912  34 128.80899 1.10081 1.900433 37.370.5772  35 19.22646 10.52353 1.632460 63.77 0.5421  36 −168.576450.12032  37 35.68369 8.40999 1.438750 94.66 0.5340  38 −24.74904 1.883711.953748 32.32 0.5901  39 26.58345 18.87835  40 48.89032 4.751271.720467 34.71 0.5835  41 −161.77170 0.00000  42 ∞ 2.30000 1.51633064.14 0.5353  43 ∞ 33.69711

TABLE 18 Example 7 WIDE MIDDLE TELE Zr 1.00 2.90 5.79 f 20.24 58.69117.18 Bf 35.21 35.21 35.21 FNo. 3.32 3.32 3.32 2ω (°) 72.92 26.56 13.64DD [15] 1.00 42.53 58.14 DD [19] 5.98 6.34 5.90 DD [22] 49.90 6.95 6.47DD [25] 14.92 15.98 1.29

TABLE 19 Example 7 Surface Number 16 KA 1.0000000E+00 A3 −1.4481371E−20A4 −2.2097151E−06 A5 1.1906712E−06 A6 −2.1344004E−07 A7 1.2774506E−08 A81.1294113E−09 A9 −2.3286340E−10 A10 1.4115083E−11 A11 4.6903088E−13 A12−1.7545649E−13 A13 9.6716937E−15 A14 6.5945061E−16 A15 −7.7270143E−17A16 −2.4667346E−19 A17 2.3248734E−19 A18 −4.1986679E−21 A19−2.5896844E−22 A20 7.5912487E−24

Example 8

FIG. 9 is a cross-sectional view of a zoom lens of Example 8. The zoomlens of Example 8 consists of, in order from the object side, a firstlens group G1, a second lens group G2, a third lens group G3, anaperture stop St, and a fourth lens group G4. The first lens group G1consists of one negative lens and five negative lenses in order from theobject side. During focusing, the first to third lenses from the objectside of the first lens group G1 remain stationary with respect to theimage plane Sim, and the fourth to sixth lenses from the object side ofthe first lens group G1 move in the direction of the optical axis. Thesign of the refractive power of each lens group and the lens groupmoving during zooming are the same as those in Example 1.

Table 20 shows basic lens data of the zoom lens of Example 8, Table 21shows values of specification and variable surface distances, and FIG.17 shows aberration diagrams in a state where the infinite object is infocus.

TABLE 20 Example 8 Si Ri Di Ndj νdj θgFj  1 −126.95737 1.85000 1.80610033.27 0.5885  2 149.63908 1.86353  3 162.56196 11.59799 1.433871 95.180.5373  4 −131.43557 0.12017  5 1767.38973 5.79391 1.433871 95.18 0.5373 6 −161.57632 6.93731  7 143.25520 6.97980 1.433871 95.18 0.5373  8−501.53280 0.12020  9 102.71367 7.30164 1.632460 63.77 0.5421 10−1279.18292 0.12015 11 52.36368 5.22130 1.695602 59.05 0.5435 1290.12596 DD [12] 13 37.28114 0.80009 2.001003 29.13 0.5995 14 12.296865.14881 15 −79.05024 0.81066 1.695602 59.05 0.5435 16 55.48025 1.2532117 −118.87335 6.29787 1.808095 22.76 0.6307 18 −11.60294 0.899941.860322 41.97 0.5638 19 139.16815 0.12024 20 29.45305 4.40793 1.55720850.70 0.5593 21 −32.29232 0.13997 22 −29.68924 0.91777 1.695602 59.050.5435 23 −137.49811 DD [23] 24 −26.11338 2.94239 1.731334 29.25 0.600625 −16.28232 0.80762 1.695602 59.05 0.5435 26 −130.41228 DD [26] 27 (St)∞ 1.85032 28 −375.35251 3.66853 1.703851 42.12 0.5727 29 −38.578520.17412 30 74.45483 6.67860 1.516330 64.14 0.5353 31 −29.71279 1.202101.882997 40.76 0.5668 32 −69.95930 34.66041 33 234.07781 4.996251.517417 52.43 0.5565 34 −40.81314 0.50000 35 40.64186 5.85957 1.48749070.24 0.5301 36 −46.57752 1.20022 1.806100 33.27 0.5885 37 34.791961.36577 38 41.96142 8.49290 1.496999 81.54 0.5375 39 −20.65900 1.576251.882997 40.76 0.5668 40 −136.64621 1.50826 41 99.48573 5.34307 1.59550939.24 0.5804 42 −34.92679 0.00000 43 ∞ 33.00000 1.608589 46.44 0.5666 44∞ 13.20000 1.516329 64.05 0.5346 45 ∞ 10.40601

TABLE 21 Example 8 WIDE MIDDLE TELE Zr 1.00 8.00 17.30 f 7.98 63.86138.11 Bf 39.63 39.63 39.63 FNo. 1.86 1.86 2.46 2ω (°) 73.62 9.68 4.52DD [12] 0.76 39.97 45.07 DD [23] 47.38 3.44 7.40 DD [26] 5.62 10.35 1.29

Table 22 shows values corresponding to Conditional Expressions (1) to(10) of the zoom lenses of Examples 1 to 8. The values shown in Table 22are values at the d line.

TABLE 22 Expression Number Example 1 Example 2 Example 3 Example 4Example 5 Example 6 Example 7 Example 8 (1) f1/fz 0.46 0.58 0.62 0.610.55 0.54 0.50 0.36 (2) νz 59.05 59.05 59.05 59.05 63.77 59.05 59.0559.05 (3) νmx − νz 35.61 35.61 35.61 35.61 30.89 35.61 35.61 36.13 (4)Nz + 0.012 × νz 2.404 2.404 2.404 2.404 2.398 2.404 2.404 2.404 (5)θgFz + 0.001625 × νz 0.639 0.639 0.639 0.639 0.646 0.639 0.639 0.639 (6)ft/f1 1.79 1.75 1.66 1.74 1.67 1.68 1.73 2.27 (7) fw/f1 0.31 0.30 0.290.30 0.29 0.29 0.30 0.13 (8) f1c/fz 0.59 0.60 0.67 0.63 0.67 0.59 0.59(9) νn 59.05 63.77 63.77 59.05 59.05 59.05 59.05 (10)  θgFn + 0.001625 ×νn 0.639 0.646 0.646 0.639 0.639 0.639 0.639

As can be seen from the above data, each zoom lens of Examples 1 to 8can be configured to have a small size since the number of lenses of thefirst lens group G1 is restricted to 6 to 8, which is relatively small.Therefore, the zoom ratio is in a range of 5.79 to 17.3 such that thehigh zoom ratio is ensured, and various aberrations including chromaticaberration are satisfactorily corrected, whereby high opticalperformance is realized.

Next, an imaging apparatus according to an embodiment of the presentinvention will be described. FIG. 18 is a schematic configurationdiagram of an imaging apparatus 10 using the zoom lens 1 according tothe above-mentioned embodiment of the present invention as an example ofan imaging apparatus of an embodiment of the present invention. Examplesof the imaging apparatus 10 include a movie imaging camera, a broadcastcamera, a digital camera, a video camera, a surveillance camera, and thelike.

The imaging apparatus 10 comprises a zoom lens 1, a filter 2 which isdisposed on the image side of the zoom lens 1, and an imaging element 3which is disposed on the image side of the filter 2. FIG. 18schematically shows the first lens group front group G1 a, the firstlens group intermediate group G1 b, the first lens group rear group G1c, and the second to fourth lens groups G2 to G4 included in the zoomlens 1. The imaging element 3 captures an optical image, which is formedthrough the zoom lens 1, and converts the image into an electricalsignal. For example, charge coupled device (CCD), complementary metaloxide semiconductor (CMOS), or the like may be used. The imaging element3 is disposed such that the imaging surface thereof is coplanar with theimage plane of the zoom lens 1.

The imaging apparatus 10 also comprises a signal processing section 5which performs calculation processing on an output signal from theimaging element 3, a display section 6 which displays an image formed bythe signal processing section 5, a zoom control section 7 which controlszooming of the zoom lens 1, and a focus control section 8 which controlsfocusing of the zoom lens 1. It should be noted that FIG. 18 shows onlyone imaging element 3, but the imaging apparatus of the presentinvention is not limited to this, and may be a so-called three-plateimaging apparatus having three imaging elements.

The present invention has been hitherto described through embodimentsand examples, but the present invention is not limited to theabove-mentioned embodiments and examples, and may be modified intovarious forms. For example, values such as the radius of curvature, thesurface distance, the refractive index, the Abbe number, and theaspheric coefficient of each lens are not limited to the values shown inthe numerical examples, and different values may be used therefor.

EXPLANATION OF REFERENCES

-   -   1: zoom lens    -   2: filter    -   3: imaging element    -   5: signal processing section    -   6: display section    -   7: zoom control section    -   8: focus control section    -   10: imaging apparatus    -   G1: first lens group    -   G1 a: first lens group front group    -   G1 b: first lens group intermediate group    -   G1 c: first lens group rear group    -   G2: second lens group    -   G3: third lens group    -   G4: fourth lens group    -   G5: fifth lens group    -   Ge: final lens group    -   L11 to L18, L21 to L24, L31 to L32, L41 to L49: lens    -   PP: optical member    -   Sim: image plane    -   St: aperture stop    -   ma, ta, wa: on-axis rays    -   mb, tb, wb: rays with maximum angle of view    -   Z: optical axis

What is claimed is:
 1. A zoom lens comprising, in order from an objectside: a first lens group that has a positive refractive power andremains stationary with respect to an image plane during zooming; aplurality of movable lens groups that move by changing distances betweengroups adjacent to each other in a direction of an optical axis duringzooming; and a final lens group that has a positive refractive power andremains stationary with respect to the image plane during zooming,wherein in the plurality of movable lens groups, at least one movablelens group has a negative refractive power, wherein the first lens grouphas an image side positive lens, which is a positive lens disposed to beclosest to the image side, and one or more positive lenses which aredisposed to be closer to the object side than the image side positivelens, and wherein all Conditional Expressions (1) to (5) are satisfied,0.25<fl/fz<0.7  (1),55<νz<68  (2),15<νmx−νz<50  (3),2.395<Nz+0.012×νz  (4), and0.634<θgFz+0.001625×νz<0.647  (5), where fl is a focal length of thefirst lens group, fz is a focal length of the image side positive lens,νz is an Abbe number of the image side positive lens at the d line, νmxis an Abbe number of a positive lens, of which the Abbe number at the dline is at a maximum value, among positive lenses disposed to be closerto the object side than the image side positive lens, Nz is a refractiveindex of the image side positive lens at the d line, and θgFz is apartial dispersion ratio of the image side positive lens between the gline and the F line.
 2. The zoom lens according to claim 1, whereinConditional Expression (6) is satisfied,1.2<ft/fl<2.8  (6), where ft is a focal length of the whole system at atelephoto end.
 3. The zoom lens according to claim 1, whereinConditional Expression (7) is satisfied,0.1<fw/fl<0.4  (7), where fw is a focal length of the whole system at awide-angle end.
 4. The zoom lens according to claim 1, wherein focusingis performed by moving one or more lenses in the first lens group in thedirection of the optical axis.
 5. The zoom lens according to claim 1,wherein in the plurality of movable lens groups, a movable lens groupclosest to the image side has a negative refractive power.
 6. The zoomlens according to claim 1, wherein the first lens group includes, inorder from the object side, a first lens group front group that has anegative refractive power and remains stationary with respect to theimage plane during focusing, a first lens group intermediate group thathas a positive refractive power and moves in the direction of theoptical axis during focusing, and a first lens group rear group that isset such that a distance in the direction of the optical axis betweenthe first lens group rear group and the first lens group intermediategroup changes during focusing and has a positive refractive power. 7.The zoom lens according to claim 6, wherein Conditional Expression (8)is satisfied,0.5<flc/fz<0.7  (8), where flc is a focal length of the first lens grouprear group.
 8. The zoom lens according to claim 6, wherein the firstlens group front group has at least one negative lens that satisfiesConditional Expressions (9) and (10),55<νn  (9), and0.635<θgFn+0.001625×νn<0.675  (10), where νn is an Abbe number of thenegative lens of the first lens group front group at the d line, andθgFn is a partial dispersion ratio of the negative lens of the firstlens group front group between the g line and the F line.
 9. The zoomlens according to claim 6, wherein the first lens group rear group has,successively in order from the object side, a cemented lens which isformed by cementing a negative lens and a positive lens in order fromthe object side, and a positive lens.
 10. The zoom lens according toclaim 6, wherein the first lens group rear group remains stationary withrespect to the image plane during focusing.
 11. The zoom lens accordingto claim 1, wherein Conditional Expression (1-1) is satisfied.0.35<fl/fz<0.65  (1-1)
 12. The zoom lens according to claim 1, whereinConditional Expression (2-1) is satisfied.56<νz<65  (2-1)
 13. The zoom lens according to claim 1, whereinConditional Expression (3-1) is satisfied.30<νmx−νz<45  (3-1)
 14. The zoom lens according to claim 1, whereinConditional Expression (6-1) is satisfied,1.5<ft/fl<2.5  (6-1), where ft is a focal length of the whole system ata telephoto end.
 15. The zoom lens according to claim 1, whereinConditional Expression (7-1) is satisfied,0.11<fw/fl<0.35  (7-1), where fw is a focal length of the whole systemat a wide-angle end.
 16. The zoom lens according to claim 6, whereinConditional Expression (8-1) is satisfied,0.55<flc/fz<0.68  (8-1), where flc is a focal length of the first lensgroup rear group
 17. The zoom lens according to claim 1, wherein theplurality of movable lens groups includes a lens group having a negativerefractive power and a lens group having a negative refractive power.18. The zoom lens according to claim 1, wherein the plurality of movablelens groups includes, in order from the object side, a lens group havinga positive refractive power, a lens group having a negative refractivepower, and a lens group having a negative refractive power.
 19. The zoomlens according to claim 1, wherein the plurality of movable lens groupsincludes, in order from the object side, a lens group having a negativerefractive power, a lens group having a positive refractive power, and alens group having a negative refractive power.
 20. An imaging apparatuscomprising the zoom lens according to claim 1.